High pressure vessel with punch



July 9, 1963 E. LUNDBLAD HIGH PRESSURE VESSEL WITH PUNCH Filed June 5, 1961 Fig.3

a944546474og/48 INVENTOR. 4 Z wv/b/m/ Y United States Patent 3,096,544 HIGH PRESSURE VESSEL WITH PUNCH Erik Lundblad, Stockholm, Sweden, assignor to Allmiinna Svenska Elelrtriska Aktiebolaget, Vasteras, Sweden, a

corporation of Sweden Filed June 5, 1961, Ser. No. 114,901 Claims priority, application Sweden June 17, 1960 5 Claims. (Cl. 1816.5)

If a cylindrical punch is pressed against an underlayer or in some other way loaded in the direction of the symmetry axis, it will crack when the pressure becomes equal to [or gueater than the compression strength of the punch material. It is known that a punch of the same material, 1 aped as a truncated cone with the smaller of the parallel surfaces of the cone of the same size as the pressure surface of the said cylindrical punch, withstands a higher pressure directed against the smaller surface than the cylindrical punch does. The more tapered the cone is, the better will be the capacity of the punch to withstand pressure.

Since the top, or pressure surface, of punches, for example if the punches are used for high pressure vessels generating pressure of a magnitude of 10,000 and over, is oiten subjected to considerable wear and defacing forces, the punches are often manufactured from cemented carbides or similar hard materials. Taking into account that the other parts of a punch do not generally become worn or defaced to the same extent as its top or pressure surface and that materials resistant to wear are often expensive and difficult to machine, it is desirable to compose the punch of at least two parts, one of which is arranged at the top of the punch and consists [of a material resistant to wear and defacement, for example a cemented carbide, and one or several other parts arranged a little 'way from the top and consisting of less resistant materials, for example tool steel or other steel. Even if the punch is made from only one material, it is often advantageous to divide it into several parts. If, therefore, the punch is damaged in those portions where it is subjected to particularly great stresses, it is under such circumstances unnecessary to replace the complete punch, but only such.

a. part or parts containing the damaged portions.

The object of the present application is a high pressure vessel comprising a pressure room and at least one punch directed towards the pressure room. The high pressure vessel according to the invention is characterised in that v the punch comprises at least two parts arranged along a double-curved, for example substantially spherical, contact surface. The double-curved surface is a non develop able surface. The punch usually has .the shape of a solid revolution, such as a body with substantially cylindrical or conical shape. It is advisable that the centre of curvature of the double-curved surface coincides substantially with the symmetry axis of the punch. In a punch with several spherical contact surfaces, the centres of curvature for the contact surfaces may with advantage substantially coincide so that the contact surfaces are substantially concentric.

' It has been found that a punch in'which adjacent parts are arranged along double-curved contact surfaces is capable of withstanding a considerably higher pressure in the high pressure vessel than a corresponding punch where the adjacent parts are arranged along flat contact surfaces. In a conical punch fiat contact surfaces between the parts, cracks usually arise which are parallel to the symmetry axis of the cone, and these appear at a considerably lower pressure than is the case with a corresponding solid punch of one material.

The invention will be more closely explained with reference to the accompanying drawing which shows different H 3,096,544 Patented July 9, 1963 embodiments as example of punches for high pressure vessels according to the invention.

FIGURE 1 shows a cylindrical punch consisting of two parts with a spherical contact surface between the parts provided to be applied in an opening to a cylindrical high pressure room.

FIGURE 2 shows a conical punch consisting of three parts with spherical contact surfaces between the parts, provided to be applied in a conical opening to a conical high pressure room or in a conical Iopening leading to a high pressure room.

FIGURE 3 shows a high pressure vessel according to the invention, in which the pressure is generated by a punch which has both conical and cylindrical pants. The cylindrical punch 11 according to FIGURE 1 consists of parts 12 and 13. The surfaces 14 and 15 are flat and perpendicular to the symmetry axis of the cylinder. The contact surface 16 between the parts is spherical and its centre of curvature is situated on the symmetry axis of the cylinder. The part 12, which is intended [to be turned towards the inner side of the pressure room may, for example, be of a cemented carbide such as Carbolloy 999 (General Electric Co.) and the part 13 of tool steel such as the tool steel C550 (Fagersta Bruk AB, Sweden) or SAE/AISI A2 with a hardness of RC5 5 The conical punch 17 according to FIGURE 2 consists of the parts 18, 19 and 2.0. The surfaces 21 and 22 are flat and perpendicular to the symmetry axis of the cone. The contact surfaces 23 and 24 between the parts 18 and 19 and between the parts 19 and 20, respectively, are spherical and concentric. The centres of curvature of the contact surfaces coincide with the symmetry axis of the cone. The part 18, which is intended to be turn d towards the inner side of the pressure room, may \for example be of la cemented carbide such as Carboloy 999 (General Electric Co.) and the part 19 of tool steel of desired hardness, such as the tool steel C550 (Fagersta Bruk AB, Sweden) or SAE/AISI A2 with a hardness of R055 and the part 20 of another tool steel such as the tool steel RO7155 '(AB Bofors, Sweden) with a hardness of RG55.

, The high pressure vessel [according to FIGURE 3 comprises a cylindrical room 25 limited by the pipe 26 and both the punches 30 and 31. The radial walls of the high pressure vessel besides the pipe 26, consist of a number of pants concentric with this, namely the cylindrical parts 27 and 28 and the partially conical part 29. On the outside the part 29 is supported by an internally conical movable casing 50 which, for example with a hydraulic press, may be forced upwards thus giving the radial walls a supporting pressure. The punch 30 is arranged on a supporting base 56, which in its turn is supported by a fixed support, not shown. The punch 30 has a conical portion essentially consisting of the parts 32 and 33 and a cylindricm portion consisting of [the part 34. The surfaces 35 and 36 are flat and perpendicular to the symmetry axis of the punch. The contact surface 37 between the parts 32 and 33, as well as the contact surface 38 between the parts 33 land 34, is spherical. The surfaces 37 and 33 are concentric. The centres of curvature for the contact surfaces lie on the symmetry axis of rthe'punch and the radius for each of the spherical contact surfaces 37 and 38 is the same as the diameter of the respective sphere segment, the spherical boundary surface of which is formed by the respective contact surface. The punch 31 is movable. The pressure in the room 25 is generated for instance by the punch 31 ebcing advanced upwards by a hydraulic press, not shown. The punch 31 has conical portions consisting of the parts 39, 40 and 41 and externally cylindrical portions consisting of the parts 42 and 43. The surfaces 44 and 45 are flat and perpendicular to the symmetry axis of the punch. The contact surface 46 between the parts 39 and 40, the contact surface 47 between the parts 40 and 42, the contact surface 48 between the parts 42 and 41 and the contact surface 49 between the parts 41 and 43, are all spherical. The surfaces 46, 47, 48 and 49 are concentric. The centres of curvature of the contact surfaces lie on the symmetry axis of the punch and the radius for each of the spherical contact surfaces 46, 47, 48 and 49 is the same size as the diameter of the respective sphere segment, the spherical boundary of which is formed of the respective contact surface.

Around the parts 41 and 43 of the lower punch is arranged a supporting body 51 which may have the form of a sleeve. The material in the supporting body consists of rubber or some other similar material having great and continual compressibility, for example, natural rubber (Quality 190 from Trelleborgs Gummifabrik AB). When the punch 31 is advanced upwards, the supporting body 51 of the part 48 is subjected to a pressure with the consequence that the supporting body exercises supporting pressure on the punch. Sealing rings 52 and 53 of toughened steel are arranged at the outer edges of the supporting body. The outer vertical surface of the part 42 is made to fit the inner cylindrical surface of the tube 28 and its upper part is bevelled to correspond with the surface of the packing ring 52 which is turned towards the part 42. The piston 30, apart from minor portions and parts of the cylinder 26, is as seen from the figures, surrounded by an electrically insulating material 54, for example mica or paper, the purpose of which is to enable electric current to be led into the pressure room via the bolt 55. The current is led off through the lower punch and further to the outer side of the apparatus where contacts may suitably be arranged so that a closed current circuit may be maintained. Within the pressure room, the current may for example be conducted by a metal thread or spiral enclosed in the material to be treated which thread or spiral is in contact with the parts 34 and 43 on respective punches.

Of course, the upper piston, like the lower piston 31, may be made movable and provided with a punch which can be pushed into the pressure chamber so that the pressure in the chamber can be generated by both the punches being pressed in. The upper piston may then e.g. be performed as the lower piston 31 with a supporting body like the body 51 surrounding the parts of the piston nearest the pressure room.

As examples of materials suitable for use for the metallic parts of the high pressure vessel according to FIGURE 3 may be mentioned: for the tube 26, tool steel WKE Brilliant (Fagersta Bruk AB, Sweden) or SAE/ AISI T4 with a hardness of RC 60; for the part 27, WKE Brilliant or SAE/AISI T4 with a hardness of RC 65, for the part 28, tool steel C550 (Fagersta Bruk A-B) or SAE/AISI A2 with a hardness of RC 62, for the part 29, tool steel C 550 or SAE/AISI A2 with a hardness of RC 55, for the member 50, tool steel R 7155 (AB Bofors, Sweden) with a hardness of RC 55, for the parts 34, 41, 42 and 43 of the pistons, a cemented carbide Coromant H 5 (Sandvikens Jernverk AB, Sweden) or Carboloy 999 (General Electric Co.), for the parts 33 and 4t), tool steel C 550 or SAE/AISI A2 with a hardness of RC 55 and for the parts 32 and 39, tool steel R0 7155 with a hardness of RC 55.

The double-curved surface does not have to be spherical as shown in the example, but may for example even be ellipsoidal or paraboloidal. If there are several contact surfaces within one punch these do not necessarily have to be concentric according to the example. In order to obtain a good contact along the common surfaces, these surfaces may with advantage be treated so that the surfaces are very even. Normally no joining arrangements are required for the different parts within a punch, but if necessary they could be joined together by mechanical arrangements such as screws, by soldering, gluing or the like.

I claim:

1. High pressure vessel comprising means forming a pressure space and at least one punch directed towards the pressure space, said punch being symmetrical about an axis running through the pressure space and comprising at least two parts engaging along a contact surface, said contact surface being a doubly curved surface the centre of curvature of which substantially coincides with the axis of symmetry of the punch and is situated on the side of the contact surface turned towards the pressure space.

2. High pressure vessel as claimed in claim 1, in which said punch is provided with several doubly curved contact surfaces with substantially coincident centres of curvature.

3. High pressure vessel as claimed in claim 1, in which said doubly curved contact surface is a spherical surface.

4. High pressure vessel comprising means forming a substantially cylindrical pressure space, means surrounding said pressure space comprising a pressure absorbing casing along the envelope surface of the space and a pair of opposed punches at the end surfaces of the space, at least one of said punches being symmetrical about an axis running through the pressure space and being movable towards the other punch and comprising at least two parts engaged along a contact surface, said contact surface being a doubly curved surface the centre of curvature of which substantially coincides with the axis of symmetry of the punch and is situated on the side of the contact surface turned towards the pressure space.

5. High pressure vessel comprising means forming a substantially cylindrical pressure space, means surrounding said pressure space comprising a pressure absorbing casing along the envelope surface of the space and a pair of opposed punches at the end surfaces of the space, at least one of said punches being movable towards the other punch, each of said punches being symmetrical about an axis running through the pressure space and having a substantially conical part, said substantially conical part comprising at least two integral parts engaging along a contact surface, said contact surface being a doubly curved surface the centre of curvature of which substantially coincides with the axis of symmetry of said punch and is situated on the side of the contact surface turned towards the pressure space.

References Cited in the file of this patent UNITED STATES PATENTS 458,076 Simmonds Aug. 18, 1891 1,836,821 Singer Dec. 15, 1931 1,843,549 Firth Feb. 2, 1932 2,272,069 Raiche Feb. 3, 1942 2,401,208 Walensky May 28, 1946 2,918,699 Hall Dec. 29, 1958 2,941,246 Bundy June 21, 1960 2,941,248 Hall June 21, 1960 2,968,837 Zeitlin et al Jan. 24, 1961 FOREIGN PATENTS 571,969 Great Britain Sept. 17, 1945 

1. HIGH PRESSURE VESSELL COMPRISING MEANS FORMING A PRESSURE SPACE AND AT LEAST ONE PUNCH DIRECTED TOWARDS THE PRESSURE SPACE, SAID PUNCH BEING SYMMETRICAL ABOUT AN AXIS RUNNING THROUGH THE PRESSURE SPACE AND COMPRISING AT LEAST TWO PARTS ENGAGING ALONG A CONTACT SURFACE, SAID CONTACT SURFACE BEING A DOUBLY CURVED SURFACE THE CENTRE OF CURVATURE OF WHICH SUBSTANTIALLY COINCIDES WITH THE AXIS OF SYMMETRY OF THE PUNCH AND IS SITUATED ON THE SIDE OF THE CONTACT SURFACE TURNED TOWARDS THE PRESSURE SPACE. 